Positive clutch plate separator system

ABSTRACT

A torque transmitting apparatus includes a cover portion generally defined by a first axis, and a flywheel coupled to the cover portion for rotation therewith. The flywheel is restrained from axial movement relative to the cover portion. The apparatus also includes a pressure plate coupled to the cover portion for rotation therewith, wherein the pressure plate is axially moveable relative to the cover portion. The apparatus also includes an intermediate plate coupled to the cover portion for rotation therewith. The intermediate plate is axially moveable relative to the cover portion and the pressure plate. The apparatus further includes a first clutch disk at least partially interposed between the pressure plate and the intermediate plate, a second clutch disk at least partially interposed between the flywheel and the intermediate plate, an axially acting biasing element for exerting an axial force between the pressure plate and the intermediate plate, and a support member extending through the biasing element.

TECHNICAL FIELD

The disclosure generally relates to dual-disk clutches for transmittingtorque in automobiles.

BACKGROUND

Friction clutches for use in transmitting rotational torque between amotor vehicle engine and a transmission are well known. One knownfriction clutch design includes two friction disks, a pressure plate, anintermediate plate, and a clutch cover mounted for rotation about acommon axis. The clutch disks, pressure plate and intermediate plate areaxially moveable relative to each other so that the pressure plate maybe moved relative to the cover to press the two friction disks and theinterposed intermediate plate axially against an engine flywheel. Aseries of drive straps, each generally including one or more resilientelements that are layered to form a leaf spring, are placed around theperipheries of the intermediate plate and pressure plate to provide abiasing force against the plates. During engagement of the clutch, theintermediate plate, pressure plate and friction disks are pressedagainst the engine flywheel, such that rotation of the flywheel causesrotation of the friction disks. During disengagement of the clutch, thedrive straps bias the intermediate plate and pressure plate in adirection away from the flywheel to separate the intermediate plate andpressure plate from the friction disks.

With many conventional friction clutches, the axial movement of theintermediate plate may be uncontrolled during engagement anddisengagement of the clutch. That is, simultaneous engagement of theintermediate plate and the pressure plate with the friction disks andsimultaneous disengagement of the friction disks from the interposedintermediate plate may not occur as desired. If the friction disks areengaged sequentially rather than simultaneously, the friction materialon one friction disk may be consumed more rapidly than the frictionmaterial on the other friction disk, thereby reducing the useful life ofthe clutch.

To ensure virtually simultaneous engagement of the friction disks,several designs have been proposed that force the travel of theintermediate plate to closely coincide with pressure plate travel. Oneknown design incorporates a mechanism that includes a separator elementbolted to the radially outer side of the intermediate plate and a leverattached to the mid-point of the drive straps that bias the pressureplate. Engagement of the separator element with the lever limits axialmovement of the intermediate plate to approximately half of the axialmovement of the pressure plate during engagement and disengagement ofthe clutch. Accordingly, the friction disks are engaged by theintermediate plate and pressure plate nearly simultaneous, providingsubstantially uniform wear of the friction disks and a smooth engagementof the clutch.

Further, the previous mechanisms to achieve simultaneous engagement havenot been adjustable. Accordingly, there exists a need for a simplifieddevice that can be easily and cost effectively affixed to a clutch toachieve the desired control of intermediate plate travel relative to thepressure plate travel.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings, illustrative embodiments are shown indetail. Although the drawings represent some embodiments, the drawingsare not necessarily to scale and certain features may be exaggerated,removed, or partially sectioned to better illustrate and explain thepresent invention. Further, the embodiments set forth herein areexemplary and are not intended to be exhaustive or otherwise limit orrestrict the claims to the precise forms and configurations shown in thedrawings and disclosed in the following detailed description.

FIG. 1 is an environmental view illustrating a clutch mounted in a heavyduty vehicle.

FIG. 2 is a view of the clutch, taken generally along line 2-2 of FIG.1.

FIG. 3 is a sectional view of the clutch, taken generally along line 3-3of FIG. 2.

FIG. 4 is a sectional view of the clutch, taken generally along line 4-4of FIG. 2.

FIG. 5 is a perspective view of the clutch, taken generally along theview of line 5-5 of FIG. 2.

FIG. 6 is an enlarged, partial cut-away view of portion A of FIG. 5.

FIG. 7 is an enlarged view of area 7 of FIG. 3, according to anembodiment, with some detail removed for clarity.

FIG. 8 is a sectional view of the clutch, taken generally along line 3-3of FIG. 2, according to another embodiment, with some detail removed forclarity.

FIG. 9 is an enlarged, partial cut-away perspective view of portion theclutch of FIG. 8, similar to the view of FIG. 6.

FIG. 10 is an enlarged view of area 10 of FIG. 8, with some detailremoved for clarity.

FIG. 11 is a sectional view of the embodiment of FIG. 8, taken generallyalong line 4-4 of FIG. 2.

FIG. 12 is a perspective view of the embodiment of FIG. 8, takengenerally along the view of line 5-5 of FIG. 2.

FIG. 13 is a perspective view of another embodiment of a clutch, withsome detail removed for clarity.

FIG. 14 is an end view of the clutch of FIG. 13.

FIG. 15 is a sectional view taken generally along line 15-15 of FIG. 14.

FIG. 16 is an exploded view of the clutch of FIG. 13.

FIG. 17 is a sectional view taken generally along line 17-17 of FIG. 14,where line 17-17 is rotated at the axis of the clutch.

DETAILED DESCRIPTION

FIG. 1 illustrates a vehicle V having a cab C heavy duty clutch 20 whichselectively transmits torque from an engine flywheel 24 to a drivenshaft 38 of a vehicle transmission T. The flywheel 24 is the drivingmember providing torque which is selectively transmitted to thetransmission T. A standard clutch release assembly 42 is employed foraffecting clutch 20 disengagement from the flywheel 24. Such movement ofrelease assembly R is achieved by depression of a clutch pedal CP in avehicle cab C, or by an electronic clutch assembly (ECA). The clutchpedal CP may be mechanically linked to release assembly 42. A fullstroke of pedal CP will fully disengage the clutch 20, moving releaseassembly 42 to an extreme right position (in the direction of the arrowR).

Referring to FIGS. 2-6, the clutch 20 is illustrated as a double-diskfriction clutch generally defined by an axis A-A (FIG. 3). The clutch 20includes a cover 22 that is detachably secured to the flywheel 24 of theinternal combustion engine E. Between the cover 22 and the flywheel 24is disposed a first friction disk 26 adjacent the flywheel 24 and an theintermediate plate 28 adjacent the first friction disk 26. A secondfriction disk 30 is disposed adjacent a transmission-facing side 32 ofthe intermediate plate 28 and a the pressure plate 34 is disposedadjacent a transmission-facing side 36 of second friction disk 30. Firstand second friction disks 26, 30 are secured for rotation on thetransmission input shaft 38, but are axially moveable in relationthereto.

The intermediate plate 28 and the pressure plate 34 are secured forrotation with the cover 22 and, like friction disks 26 and 30, areaxially moveable in relation thereto. In the illustrated exemplaryembodiment, the pressure plate 34 abuts a diaphragm spring 40 thatmoveably connects the pressure plate 34 to a release mechanism 42. Therelease mechanism 42 is selectively controlled by a vehicle operator toengage and disengage the clutch 20. However, it will be appreciated thatthe clutch 20 can be used with a variety of clamp-load generatingrelease mechanisms besides a diaphragm spring. One well known example isthe use of a plurality of levers and compression springs. Anotheralternative is a centrifugally actuated clutch having both anintermediate plate and a pressure plate. In the centrifugally actuatedclutch, the clamping load is generated by pivoted weights, which swingradially outwardly with rotation of the clutch assembly.

Referring now specifically to FIGS. 4 and 5, the intermediate plate 28and the pressure plate 34 are moveably connected to the cover 22 byfirst and second drive straps 44 and 46, respectively. The drive straps44, 46 preferably include a plurality of resilient elements that arelayered together to form a leaf spring, as is known. The first drivestrap 44 provides a force on the intermediate plate 28 for biasing theintermediate plate 28 in a direction toward the pressure plate 34.Similarly, the second drive strap 46 provides a force against thepressure plate 34 to ensure that the pressure plate 34 is in continuouscontact with the diaphragm spring 40. In return, the diaphragm spring 40applies a clamping force against the pressure plate 34 when engagementof the clutch 20 is desired. While FIGS. 4 and 5 show only one pair ofdrive straps 44, 46 for each of the intermediate plate 28 and thepressure plate 34, respectively, a plurality of the drive straps 44 and46 are distributed about the peripheries of the intermediate plate 28and the pressure plate 34 in the exemplary embodiment illustrated.

Referring again to FIG. 4, a first end 48 of the second drive strap 46is fixedly secured to a flange portion 50 of the pressure plate 34 by afastener 52, such as a rivet or the like. A second end 54 of the seconddrive strap 46 is removably connected to the cover 22 by a drive strapfastener 56, such as a threaded bolt or the like. A washer 58 may bedisposed between a head 59 of the fastener 56 and the second drive strap46 to ensure adequate contact pressure is distributed over second end 54of the second drive strap 46.

With continuing reference to FIG. 4, a first end 60 of the first drivestrap 44 is fixedly secured to the intermediate plate 28 by a fastener64, such as a rivet or the like, while a second end 62 of the firstdrive strap 44 is removably connected to the cover 22. In the embodimentillustrated, the first drive strap 44 is preferably attached to thecover 22 by the fastener 56, which may be a threaded bolt or the like. Agenerally cylindrical sleeve 66 extends between the second end 62 of thefirst drive strap 44 and the second end 54 of the second drive strap 46.Accordingly, the first drive strap 44 and the second drive strap 46 arefixedly attached to the cover 22 with a single fastener 56, although thefirst drive strap 44 and the second drive strap 46 may not be fixedlyattached to the cover 22 with a single fastener.

Referring to FIGS. 6 and 7, the intermediate plate 28 includes aplurality of intermediate attachment portions 70 having an aperture 72formed therein, and the pressure plate 34 includes a plurality ofpressure attachment portions 74 having an aperture 76 formed therein. Aplurality of biasing members 80 are interposed between the intermediateplate 28 and the pressure plate 34. Each biasing member 80 includes afirst end 82 that abuts one of the pressure attachment portions 74, anda second end 84 that abuts one of the intermediate attachment portions70. As illustrated in FIG. 7, when the friction disks 26, 30 contact theflywheel 24, intermediate plate 28, and the pressure plate 34, thebiasing members 80 are compressed such that the biasing members 80 exertan axial force (generally parallel to the axis A-A) to urge the pressureplate 34 away from the intermediate plate 28. In the embodimentillustrated, the clutch 20 includes four biasing members 80, althoughother suitable numbers of biasing members may be used.

Each biasing member 80 includes a first support member 90 interposedtherethrough. As illustrated, the first member 90 is slidably interposedthrough one of the apertures 72 of the intermediate plate 28 and coupledto one of the apertures 76 of the pressure plate 34 to permit the firstmember 90 to axially translate within the aperture 72 as theintermediate plate 28 moves axially relative to the pressure plate 34.In the embodiment illustrated, the first member 90 is threadablyreceived within the aperture 76, although the first member 90 may becoupled with the pressure plate 34 and the intermediate plate 28 in anysuitable manner to retain the biasing element 80 in a desired positionwhile permitting the intermediate plate 28 to move axially relative tothe pressure plate 34.

When the clutch 20 is disengaged, that is, when the release assembly 42is moved away from the pressure plate 34, the pressure plate 34 is urgedto move away from the flywheel 24 due to the biasing force of the seconddrive strap 46. Virtually simultaneously, the intermediate plate 28automatically moves away from the flywheel 24 due to the biasing forceof the first drive strap 44. Due to the biasing force that the biasingmember 80 exerts between the pressure plate 34 and the intermediateplate 28, the axial distance the intermediate plate 28 moves isapproximately one-half the axial distance the pressure plate 34 moves.In this manner, it is ensured that first and second friction disks 26,30 are disengaged virtually simultaneously.

It will be appreciated that axial movement of the intermediate plate 28relative to the pressure plate 34 can be easily modified by altering thespring rates of the biasing member 80, the first drive strap 44, and thesecond drive strap 46. In the embodiment illustrated, the spring ratesof the first drive strap and the biasing member are about equal,although other spring rates may be used, as desired.

Referring to FIGS. 8-12, an alternate exemplary embodiment of theinventive system is shown in detail. In this exemplary approach, aclutch 220 is provided that is substantially similar to the clutch 20described in the first embodiment with a least one exception, namely,the biasing member may be adjustably preloaded, as discussed in greaterdetail below.

The clutch 220 includes a cover 222 that is detachably secured to theflywheel 224 of the internal combustion engine E. Between the cover 222and the flywheel 224 is disposed a first friction disk 226 adjacent theflywheel 224 and an the intermediate plate 228 adjacent the firstfriction disk 226. A second friction disk 230 is disposed adjacent atransmission-facing side 232 of the intermediate plate 228 and apressure plate 234 is disposed adjacent a transmission-facing side 236of second friction disk 230. First and second friction disks 226, 230are secured for rotation on the transmission input shaft 238, but areaxially moveable in relation thereto.

The intermediate plate 228 and the pressure plate 234 are secured forrotation with the cover 222 and, like friction disks 226 and 230, areaxially moveable in relation thereto. In the illustrated embodiment, thepressure plate 234 abuts a diaphragm spring 240 that moveably connectsthe pressure plate 234 to a release mechanism 242. The release mechanism242 is selectively controlled by a vehicle operator to engage anddisengage the clutch 20. However, it will be appreciated that the clutch220 can be used with a variety of clamp-load generating releasemechanisms besides a diaphragm spring. One well known example is the useof a plurality of levers and compression springs. Another illustrativealternative is a centrifugally actuated clutch having both anintermediate plate and a pressure plate. In the centrifugally actuatedclutch, the clamping load is generated by pivoted weights, which swingradially outwardly with rotation of the clutch assembly.

Referring now specifically to FIGS. 9, 11, and 12, the intermediateplate 228 and the pressure plate 234 are moveably connected to the cover222 by first and second the drive straps 244 and 246, respectively. Thedrive straps 244, 246 preferably include a plurality of resilientelements that are layered together to form a leaf spring, as is known.The first drive strap 244 provides a force on the intermediate plate 228for biasing the intermediate plate 228 in a direction toward thepressure plate 234. Similarly, the second drive strap 246 provides aforce against the pressure plate 234 to ensure that the pressure plate234 is in continuous contact with the diaphragm spring 240. In return,the diaphragm spring 240 applies a clamping force against the pressureplate 234 when engagement of the clutch 220 is desired. While FIGS. 4,5, and 9 show only one pair of drive straps 244, 246 for each of theintermediate plate 228 and the pressure plate 234, respectively, aplurality of the drive straps 244 and 246 are distributed about theperipheries of the intermediate plate 228 and the pressure plate 234 inthe exemplary embodiment illustrated.

Referring again to FIG. 11, a first end 248 of the second drive strap246 is fixedly secured to a flange portion 250 of the pressure plate 234by a fastener 252, such as a rivet or the like. A second end 254 of thesecond drive strap 246 is removably connected to the cover 222 by adrive strap fastener 256, such as a threaded bolt or the like. A washer258 may be disposed between a head 259 of the fastener 256 and thesecond drive strap 246 to ensure adequate contact pressure isdistributed over second end 254 of the second drive strap 246.

With continuing reference to FIG. 11, a first end 260 of the first drivestrap 244 is fixedly secured to the intermediate plate 228 by a fastener264, such as a rivet or the like, while a second end 262 of the firstdrive strap 244 is removably connected to the cover 222. In theembodiment illustrated, the first drive strap 244 is preferably attachedto the cover 222 by the fastener 256, which may be a threaded bolt orthe like. A generally cylindrical sleeve 266 extends between the secondend 262 of the first drive strap 244 and the second end 254 of thesecond drive strap 246. Accordingly, the first drive strap 244 and thesecond drive strap 246 are fixedly attached to the cover 222 with asingle fastener 256, although the first drive strap 244 and the seconddrive strap 246 may not be fixedly attached to the cover 222 with asingle fastener.

Referring to FIG. 10, the intermediate plate 228 includes a plurality ofintermediate attachment portions 270 having an aperture 272 formedtherein, and the pressure plate 234 includes a plurality of pressureattachment portions 274 having an aperture 276 formed therein. Aplurality of biasing members 280 are interposed between the intermediateplate 228 and the pressure plate 234. Each biasing member 280 includes afirst end 282 that abuts one of the pressure attachment portions 274,and a second end 284 that abuts one of the intermediate attachmentportions 270. As illustrated in FIG. 8, when the friction disks 226, 230contact the flywheel 224, intermediate plate 28, and the pressure plate234, the biasing members 280 are compressed such that the biasingmembers 280 exert an axial force (generally parallel to the axis B-B) tourge the pressure plate 234 away from the intermediate plate 28. In theembodiment illustrated, the clutch 220 includes four biasing members280, although other suitable numbers of biasing members may be used.

Each biasing member 280 includes an elongated first member 290interposed therethrough. The first member 290 has a coupling member 292,such as a threaded nut attached thereto. The first member 290 includes acollar 294 having a larger diameter than the remainder of the firstmember 290. As illustrated, the first member 290 is slidably interposedthrough one of the apertures 272 of the intermediate plate 228 andthreadably received in one of the apertures 276 of the pressure plate234 to permit the first member 290 to axially translate within theaperture 272 as the intermediate plate 228 moves axially relative to thepressure plate 234. The first member 290 is threaded to the aperture276, generally indicated at 300. In the embodiment illustrated, thefirst member 290 is threadably received within the aperture 276 foradjusting the collar 294 axially relative to the pressure plate 234,although the first member 290 may be coupled with the pressure plate 234and the intermediate plate 228 in any suitable manner to retain thebiasing element 280 in a desired position while permitting theintermediate plate 228 to move axially relative to the pressure plate234.

As best illustrated in FIG. 10, when the second friction disk 230 isclamped between the pressure plate 234 and the intermediate plate 228,the biasing element 280 is compressed. The threaded engagement betweenthe first member 290 and the pressure plate 234 permits the biasingelement to be preloaded when in the configuration of FIG. 10, asdesired. Accordingly, a user may increase or decrease the rate ofdeparture between the pressure plate 234 and the intermediate plate 228by adjusting the first members 290. In one embodiment of adjusting thepreload, a user may determine a selected first amount of preload forcefor the biasing member. After operating for a period of time, if thewear on one of the friction disks 226, 230 exceeds the other, the firstmembers 290 may be rotated relative to the pressure plate 234 to changethe axial position of the first members 290 relative to the pressureplate 234, thereby changing the preload on the biasing members 288. Thischange in preload may result in an increased wear rate on the frictiondisk that was determined to have the lesser amount of wear as comparedto the friction disk that was determined to have the greater amount ofwear, thereby increasing the life of the clutch 220. The coupling member292 may be used to prevent unwanted rotation of the first member 290, asis known.

Although the first members 90, 290 are illustrated with threaded surfaceportions, the first members 90, 290 may include any surface features foraxially restraining at least one of the pressure plate and theintermediate plate relative to the first member. Further, while thefirst member 290 illustrated with a collar 294 for axially restrainingthe biasing element 280 relative to the first member, the first member290 may include any surface feature suitable for axially restraining thebiasing element 280 relative to the first member 290.

Referring to FIGS. 13-16, an alternate exemplary embodiment of theinventive system is shown in detail. In this exemplary approach, aclutch 420 is provided that is substantially similar to the clutch 20described in the first embodiment with a least one exception, namely,the drive straps may not be used. Specifically, the first drive straps44 may omitted and the intermediate plate coupled for rotation with thecover, flywheel and pressure plate as described herein.

The clutch 420 includes a cover 422 that is detachably secured to aflywheel 424 of an internal combustion engine, such as the internalcombustion engine E. Between the cover 422 and the flywheel 424 isdisposed a first friction disk 426 adjacent the flywheel 424 and an theintermediate plate 428 adjacent the first friction disk 426. A secondfriction disk 430 is disposed adjacent a transmission-facing side 432 ofthe intermediate plate 428 and a pressure plate 434 is disposed adjacenta transmission-facing side 436 of second friction disk 430. First andsecond friction disks 426, 430 are secured for rotation on atransmission input shaft 438, but are axially moveable in relationthereto.

The intermediate plate 428 and the pressure plate 434 are secured forrotation with the cover 422 and the flywheel 424 and, like frictiondisks 426 and 430, are axially moveable in relation thereto. In theillustrated embodiment, the pressure plate 434 abuts a diaphragm spring440 that moveably connects the pressure plate 434 to a release mechanism442. The release mechanism 442 is selectively controlled by a vehicleoperator to engage and disengage the clutch 420. However, it will beappreciated that the clutch 420 can be used with a variety of clamp-loadgenerating release mechanisms besides a diaphragm spring. One well knownexample is the use of a plurality of levers and compression springs.Another illustrative alternative is a centrifugally actuated clutchhaving both an intermediate plate and a pressure plate. In thecentrifugally actuated clutch, the clamping load is generated by pivotedweights, which swing radially outwardly with rotation of the clutchassembly. As discussed in greater detail below, the flywheel 424includes a plurality of generally cylindrical apertures 444 for guidingthe intermediate plate axially relative to the flywheel 424.

The cover 422 includes a plurality of flywheel attachment portions 450.The intermediate plate 428 includes a plurality of lugs 452 (FIGS. 13and 16) that are interposed between pairs of the flywheel attachmentportions 450 for coupling the intermediate plate 428 for rotation withthe cover 422. The lugs 452 include generally tubular alignment members454 extending therefrom. As best seen in FIG. 17, the intermediate plate428 is rotatably connected to the cover 222 by a plurality of drivestraps 446. The drive straps 446 may include a plurality of resilientelements that are layered together to form a leaf spring, as is known.The drive strap 458 provides a force against the pressure plate 434 toensure that the pressure plate 434 is in continuous contact with thediaphragm spring 440. In return, the diaphragm spring 440 applies aclamping force against the pressure plate 434 when engagement of theclutch 420 is desired. A plurality of the drive straps 446 aredistributed about the peripheries of the intermediate plate 428 and thepressure plate 434 in the exemplary embodiment illustrated.

Referring again to FIG. 17, a first end 460 of the drive strap 458 isfixedly secured to a flange portion 462 of the pressure plate 434 by afastener 464, such as a rivet or the like. A second end 466 of the drivestrap 446 is removably connected to the cover 422 by a drive strapfastener 468, such as a threaded bolt or the like.

Referring to FIGS. 15 and 16, the intermediate plate 428 includes aplurality of intermediate attachment portions 470 having an aperture 472formed therein, and the pressure plate 434 includes a plurality ofpressure attachment portions 474 having an aperture 476 formed therein.A plurality of biasing members 480 are interposed between theintermediate plate 428 and the pressure plate 434. Each biasing member480 includes a first end 482 that abuts one of the pressure attachmentportions 474, and a second end 484 that abuts one of the intermediateattachment portions 470. When the friction disks 426, 430 contact theflywheel 424, the intermediate plate 428, and the pressure plate 434,the biasing members 480 are compressed such that the biasing members 480exert an axial force (generally parallel to the axis C-C) to urge thepressure plate 434 away from the intermediate plate 428. In theembodiment illustrated, the clutch 420 includes four biasing members480, although other suitable numbers of biasing members may be used.

Each biasing member 480 includes an elongated first member 490interposed therethrough. The first member 490 has a coupling member 492,such as a threaded nut attached thereto. The first member 490 includes acollar 494 having a larger diameter than the remainder of the firstmember 490. As illustrated, the first member 490 is slidably interposedthrough one of the apertures 472 of the intermediate plate 428 andthreadably received in one of the apertures 476 of the pressure plate434 to permit the first member 490 to axially translate within theaperture 472 as the intermediate plate 428 moves axially relative to thepressure plate 434. The first member 490 is threaded to the aperture476, generally indicated at 500. In the embodiment illustrated, thefirst member 490 is threadably received within the aperture 476 foradjusting the collar 494 axially relative to the pressure plate 434,although the first member 490 may be coupled with the pressure plate 434and the intermediate plate 428 in any suitable manner to retain thebiasing element 480 in a desired position while permitting theintermediate plate 428 to move axially relative to the pressure plate434.

As best illustrated in FIG. 15, when the second friction disk 430 isclamped between the pressure plate 434 and the intermediate plate 428,the biasing element 480 is compressed. The threaded engagement betweenthe first member 490 and the pressure plate 434 permits the biasingelement to be preloaded when in the configuration of FIG. 10, asdesired. Accordingly, a user may increase or decrease the rate ofdeparture between the pressure plate 434 and the intermediate plate 428by adjusting the first members 490. In one embodiment of adjusting thepreload, a user may determine a selected first amount of preload forcefor the biasing member. After operating for a period of time, if thewear on one of the friction disks 426, 430 exceeds the other, the firstmembers 490 may be rotated relative to the pressure plate 434 to changethe axial position of the first members 490 relative to the pressureplate 434, thereby changing the preload on the biasing members 488. Thischange in preload may result in an increased wear rate on the frictiondisk that was determined to have the lesser amount of wear as comparedto the friction disk that was determined to have the greater amount ofwear, thereby increasing the life of the clutch 420. The coupling member492 may be used to prevent unwanted rotation of the first member 490, asis known. Further, the biasing member 488 may not be preloaded.

The alignment members 454 extend into the apertures 444 and are axiallymoveable relative thereto as the intermediate plate 428 moves axiallyrelative to the flywheel 424. In another embodiment, a plurality ofbiasing members 490, such as coil springs, may be interposed between theintermediate plate 428 and the flywheel 424 to urge the intermediateplate 428 to move generally in the direction of the arrow R as thepressure plate 434 moves generally in the direction of the arrow R. Thecombined force of the biasing members 510 of the clutch 420 may be aboutequal to the combined force of the biasing members 480 to urge theintermediate plate to move about half of the axial distance moved by thepressure plate 434 relative to the flywheel during clutch engagement anddisengagement.

Although the steps of operating and assembling the clutches 20, 220, 420may be listed in an order, the steps may be performed in differingorders or combined such that one operation may perform multiple steps.Furthermore, a step or steps may be initiated before another step orsteps are completed, or a step or steps may be initiated and completedafter initiation and before completion of (during the performance of)other steps.

The preceding description has been presented only to illustrate anddescribe exemplary embodiments of the methods and systems of the presentinvention. It is not intended to be exhaustive or to limit the inventionto any precise form disclosed. It will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted for elements thereof without departing from the scope of theinvention. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from the essential scope. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims. The invention may be practiced otherwise than isspecifically explained and illustrated without departing from its spiritor scope. The scope of the invention is limited solely by the followingclaims.

What is claimed is:
 1. A torque transmitting apparatus comprising: acover portion generally defined by a first axis; a flywheel coupled tothe cover portion for rotation therewith, wherein the flywheel isrestrained from axial movement relative to the cover portion a pressureplate coupled to the cover portion for rotation therewith, wherein thepressure plate is axially moveable relative to the cover portion; anintermediate plate coupled to the cover portion for rotation therewith,wherein the intermediate plate is axially moveable relative to the coverportion and the pressure plate; a first clutch disk at least partiallyinterposed between the flywheel and the intermediate plate; a secondclutch disk at least partially interposed between the pressure plate andthe intermediate plate; an axially acting biasing element for exertingan axial force between the pressure plate and the intermediate plate; asupport member extending through the biasing element, the pressureplate, and the intermediate plate; a first drive strap interconnectingthe pressure plate and the cover; and a second drive strapinterconnecting the intermediate plate and the cover, wherein the firstdrive strap and the second drive strap are attached to the cover only bya single drive strap fastener.
 2. The apparatus of claim 1, wherein thefirst drive strap extends circumferentially and axially between thepressure plate and the cover for providing a biasing force therebetween.3. The apparatus of claim 2, wherein the second drive strap extendscircumferentially and axially between the intermediate plate and thecover for providing a biasing force therebetween.
 4. The apparatus ofclaim 1, wherein the drive strap fastener is interposed through anaperture in the cover.
 5. The apparatus of claim 1, wherein the biasingelement is preloaded, at least in part, by the support member.
 6. Theapparatus of claim 1, wherein the support member includes a firstsurface portion for axially restraining the biasing element relative tothe support member, and a second surface portion for axially restrainingat least one of the pressure plate and the intermediate plate relativeto the support member.
 7. A method of assembling a clutch, comprising:interposing a first friction member between a flywheel and anintermediate plate; interposing a second friction member between apressure plate and the intermediate plate; positioning a biasing memberadjacent the pressure plate and the intermediate plate such that thebiasing member will resiliently bias the pressure plate away from theintermediate plate; interposing a support member through the biasingmember; positioning a portion of a first drive strap to the intermediateplate; positioning a portion of a second drive strap to the pressureplate; and attaching a second portion of the first drive strap and asecond portion of the second drive strap to a cover by a single drivestrap fastener.
 8. The method of claim 7, further comprising adjustingan initial preload force on the biasing member to provide an adjustedpreload force.
 9. The method of claim 7, further comprising adjustablycoupling the support member to one of the pressure plate and theintermediate plate.
 10. The method of claim 7, the second drive strapinterconnects the intermediate plate and the cover and extendscircumferentially and axially between the intermediate plate and thecover for providing a biasing force therebetween.
 11. The method ofclaim 10, the first drive strap interconnects the pressure plate and thecover and extends circumferentially and axially between the pressureplate and the cover for providing a biasing force therebetween.
 12. Amethod of assembling a clutch, comprising: interposing a first frictionmember between a flywheel and an intermediate plate; interposing asecond friction member between a pressure plate and the intermediateplate; positioning a biasing member adjacent the pressure plate and theintermediate plate such that the biasing member will resiliently biasthe pressure plate away from the intermediate plate; determining aselected first amount of preload force for the biasing member; adjustingthe preload on the biasing member to provide a second amount of preloadforce wherein the adjusting comprises at least in part, a selectiverotating of a support member.
 13. The method of claim 12, furthercomprising interposing the support member at least partially within thebiasing member.
 14. The method of claim 12, further comprising a supportmember interposed within the biasing member and coupled to at least oneof the pressure plate and intermediate plate, wherein the support membermay be adjusted for axial displacement relative to at least one of thepressure plate and the intermediate plate.
 15. The method of claim 12,further comprising coupling a first drive strap to the intermediateplate and a cover, wherein the first drive strap extendscircumferentially and axially between the intermediate plate and thecover for providing a biasing force therebetween.
 16. The method ofclaim 15, further comprising coupling a second drive strap to thepressure plate and the cover, wherein the second drive strap extendscircumferentially and axially between the pressure plate and the coverfor providing a biasing force therebetween, and wherein the first drivestrap and the second drive strap are connected to the cover with asingle fastener.
 17. A torque transmitting apparatus comprising: a coverportion generally defined by a first axis; a flywheel coupled to thecover portion for rotation therewith, wherein the flywheel is restrainedfrom axial movement relative to the cover portion a pressure platecoupled to the cover portion for rotation therewith, wherein thepressure plate is axially moveable relative to the cover portion; anintermediate plate coupled to the cover portion for rotation therewith,wherein the intermediate plate is axially moveable relative to the coverportion and the pressure plate; a first clutch disk at least partiallyinterposed between the flywheel and the intermediate plate; a secondclutch disk at least partially interposed between the pressure plate andthe intermediate plate; an axially acting biasing element for exertingan axial force between the pressure plate and the intermediate plate; asupport member extending through the biasing element, the pressureplate, and the intermediate plate; a first drive strap interconnectingthe pressure plate and the cover; and a second drive strapinterconnecting the intermediate plate and the cover, wherein the firstdrive strap and the second drive strap are coupled to at least one drivestrap fastener, and where the at least one drive strap fastener isinterposed through an aperture in the cover.